Apparatus and method for drawing of glass fiber

ABSTRACT

An apparatus and method for use with a bushing assembly of the type wherein glass fibers are drawn through an orifice plate having a flat undersurface against which bulk gas is directed to effect cooling and fiber attentuation. A selectively adjustable bulk gas nozzle has a plurality of discharge conduits with valves therein which are adjustable and capable of being selectively operated to close the conduits or return the conduits to a preset open condition. The nozzle and/or a binder applicator are supported for select movement toward and away from the path of the fiber being drawn from the orifice plate. A detector senses the presence of fiber being drawn from the orifice plate and, in the event of fiber break-out, initiates a series of steps to warn the operator of the bushing assembly and, in the event the break-out condition is not corrected, shut down the drawing operation.

This is a division of application Ser. No. 865,961 filed Dec. 30, 1977now U.S. Pat. No. 4,149,865 granted Apr. 17, 1979.

BACKGROUND OF THE INVENTION

The present invention relates to a control system for a bushing assemblyused in the drawing of glass fibers and, in particular, is directed tosuch a system for use with a "bulk gas" drawing assembly of the typedisclosed in U.S. Pat. No. 3,905,790 to Edward T. Strickland. In itsmore specific aspects, the invention is concerned with an improvement inthe control system and bulk gas supply nozzle of our U.S. Pat. No.3,986,853.

The system of our U.S. Pat. No. 3,986,853 relied upon a human operatorto (1) sense the occurrence of a break-out of the fiber being drawn and(2) activate a control in response to the sensed condition. Theactivation of the control functioned to lower the temperature of thebushing assembly, increase the rate of flow of bulk gas against theorifice plate of the assembly, and reduce the drawing action of thecollet used to draw the fiber from the plate. The system provided amanually operated air lance for startup and clearing of the plate.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for the automaticdetection of fiber break-out in a glass fiber drawing operation and theinitiation of a series of corrective steps in the event of suchbreak-out. Automatic detection is achieved by electronically sensing thepresence or absence of the glass fiber being drawn. The sequence ofsteps initiated in response to the detection includes: an initial alarm;a time delay; and, in the event a human operator does not correct thesituation during the time delay period, the automatic initiation of a"break-out mode" of operation. Initiation of the break-out mode lowersbushing temperature, retracts the bulk air supply nozzle and terminatesthe supply of bulk air, opens a clearing air supply to direct clearingair across and against the orifice plate of the bushing, and shuts offthe drawing collet.

The apparatus of the invention also includes an improved nozzle fordirecting bulk gas against the orifice plate of a bushing used in thedrawing of glass fiber. The nozzle is designed to provide for theadjustment of the gas supply to discrete areas of the plate and includesa plurality of outlet conduits, each of which is provided with a valvewhich may be adjusted to selectively vary the volume of gas passingtherethrough, or turned to a full shut-off position. Adjustment of thevalves is provided by stops which enable the individual valves to bereturned to the adjusted flow position from the shut-off position,without the necessity of readjustment.

The apparatus of the invention also includes a moveable support for thebulk gas supply nozzle to provide for the selective movement of thenozzle toward and away from the path of fibers being drawn from abushing assembly during the flood clearing step. This support operatesin conjunction with the break-out detector to move the bulk gas supplynozzle away from said path in the event the detector senses a break-out.Thus, the nozzle is removed to a position where it does not interferewith clearing operations and wherein it is not subject to fouling byfalling glass.

A principal object of the invention is to provide an apparatus andmethod for the drawing of glass fibers wherein fiber break-out isautomatically detected and corrective steps are initiated in response tosuch detection.

Another object of the invention is to provide such an apparatus andmethod wherein the corrective steps accomplish shutdown of the drawingoperation and wherein alarm and delay steps take place in advance ofsuch corrective steps.

A further object of the invention is to provide a bulk gas supply nozzlefor use in a glass fiber drawing assembly wherein the nozzle isselectively adjustable to adjust the flow of gas to discrete areas ofthe orifice plate of the assembly.

Still another object related to the latter object is to provide such anozzle wherein the supply of gas to discrete areas of the orifice platemay be selectively shut off or opened during flood clearing and, uponopening, a preadjusted flow condition is established, without need ofreadjustment.

Yet another object of the invention is to provide a remotely operablemounting means for moveably supporting a bulk gas supply nozzle beneaththe orifice plate of a glass fiber drawing assembly.

The foregoing and other objects of the invention will become apparentwhen viewed in light of the accompanying drawings and following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, with parts thereof broken away and shownin section, illustrating a glass fiber drawing assembly embodying theinventive bulk gas supply nozzle and the moveable support meanstherefor;

FIG. 2 is a cross-sectional elevational view similar to FIG. 1, taken at90° from the view of FIG. 1;

FIG. 3 is a diagrammatic view illustrating the control system of thepresent invention incorporated into a glass fiber drawing assembly;

FIG. 4 is a cross-sectional elevational view of the bulk gas supplynozzle of the invention, taken on the plane designated by line 4--4 ofFIG. 1;

FIG. 5 is a cross-sectional view taken on the plane designated by line5--5 of FIG. 4, illustrating a valve of the bulk gas supply nozzle in anadjusted restricted flow position;

FIGS. 6 and 7 are cross-sectional views taken on the planes designatedby lines 6--6 and 7--7 of FIG. 5;

FIG. 8 is a cross-sectional view taken on the plane designated by line8--8 of FIG. 4, illustrating a valve of the bulk supply nozzle in theshut-off position;

FIGS. 9 and 10 are cross-sectional views taken on the planes designatedby line 9--9 and 10--10 of FIG. 8;

FIG. 11 is a logic flow diagram illustrating the mode of operation ofthe control system when the automatic break-out control is locked in theinactive (reset) position; and

FIG. 12 is a logic flow diagram illustrating the mode of operation ofthe control system when the automatic break-out control is locked in theactive (automatic) position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1, 2 and 3, a bushing assembly designated 10, isshown mounted beneath a flow block 12 which defines the underside of adirect-melt forehearth. The forehearth contains molten glass 14. A flowpassage 16 formed in the flow block 12 communicates the glass with aflow chamber 18 formed in the bushing assembly 10. The bottom of thechamber 18 is closed by an orifice plate 20 having a perforated drawingarea 22 through which glass fibers, designated 14a, are drawn.

The basic drawing assembly is completed by a gathering shoe 23; a binderapplicator assembly 24; a collet winding mechanism 26; a bulk gas supplynozzle 28; and opposed gas supply nozzles 30. The nozzles 30 are of thetype disclosed in U.S. Pat. No. 4,033,742 and, in the preferredembodiment, are disposed at an angle of from 30° to 60° degrees to theundersurface of the orifice plate 20. As will become more apparent fromthe subsequent discussion, the nozzles 30 come into operation when thecontrol system of the present invention is in the automatic break-outmode. These nozzles may also be used for any of the purposes disclosedin U.S. Pat. No. 4,033,742 (e.g., to provide a multiple air lance effectin starting up, clearing, and maintaining a flow of individual glassfibers through the orifices of the orifice plate.

The nozzles 30 are fixedly mounted beneath the orifice plate 20 toeither side of the orifice formed therein. As so mounted, the nozzles 30are outside the path of the fibers 14a and sufficiently removed from themain operating area of the drawing assembly as to not interfere withstart-up, clearing or normal drawing operation.

The bulk gas supply nozzle 28 is mounted beneath the bushing assembly 10on the moveable support, designated 32, of the present invention. Inaddition to the nozzle 28, the support 32 also carries the gatheringshoe 23 and the binder applicator 24. The support comprises: a carriage34; guide elements 36 fixed to either side of the carriage; tracks 38slideably receiving the guide elements 36, said tracks being fixedlysecured to fixed frame members 40; a pneumatic cylinder 42 having itsbody secured to the frame members 40 and its piston rod 44 secured tothe carriage 44; and, brace members 46 securing the nozzle 28 to thecarriage 34. In the preferred embodiment, the brace members 46 areselectably adjustable to adjust the angle of the nozzle 28 relative tothe carriage. The guide elements 36 and tracks 38 guide the carriage formovement in a rectilinear path toward and away from the path of thefibers 14a being drawn from the bushing assembly 10. Extension of thecylinder 42 on the introduction of air thereinto functions to move thecarriage toward the path of the fibers being drawn. Suitable stops (notillustrated) limit the extent of extension so that the nozzle 28 isaccurately positioned at the desired position beneath the orifice plate20 when the carriage is extended. Retraction of the carriage 34 isachieved by releasing the air pressure from the cylinder 46, whereby aspring 48 within the cylinder functions to retract the rod 44.

The gathering shoe 23 and binder applicator 24 are carried by a tray 50fixedly secured to the carriage 34 for movement therewith. The tray 50contains a reservoir of binder compound and carries an applicator roll52 positioned so as to be partially submerged within the compound. Theroll 52 is mounted on the tray for free rotation about an axle 54extending generally normal to the path of the fibers 14a. When thecarriage 34 is in the extended condition, fibers 14a engage both thegathering shoe 23 and the roll 52. An arm 56 supports the gathering shoe23 on the tray 50 so that, when extended, the gathering shoe is alignedwith the path of the fibers 14a.

The winder 26 is of the type disclosed in U.S. patent application Ser.No. 735,000, filed on Oct. 22, 1976, now U.S. Pat. No. 4,076,181 byCharles H. Coggin, one of the co-inventors herein. Such a winder isideally suited for the direct winding of precision packages in that itprovides for drawing of the fibers from the gathering shoe at asubstantially constant angle. The constant angle is maintained byincrementally moving the collect of the winder away from the guide asthe package grows. As shown in FIGS. 1 and 2, the collet and guide ofthe winder are designated by the numerals 58 and 60, respectively. Apackage 62 is shown partially formed on the collet. As the packagegrows, the guide 60 is depressed and this, in turn, triggers the controlcircuit (not illustrated) of the winder to incrementally move the colletaway from the guide.

A water supply nozzle 64 is mounted beneath and to one side of thebushing assembly 10 to selectively spray a fine mist of water againstthe fibers 14a being drawn from the assembly. Water is supplied to thenozzle by a conduit 66. A solenoid operated valve 68 normally maintainsthe conduit in a closed condition. As will be seen from the followingdiscussion, the water supply nozzle is open during the start-upoperation and closed during the normal operating mode when fibers arebeing drawn from the bushing.

FIG. 3 illustrates the break-out detector employed to trigger theautomatic break-out mode of the inventive control system. This detectoris mounted between the applicator roll and the gathering shoe 23 and isfocused to detect the presence or absence of a strand of fibers 14abeing drawn from the bushing 20 to the collet 58. The detector isdesignated in its entirety by the numeral 70 and comprises an energysource 72 in the form of a pulsed (i.e., modulated) light emitting diode(LED) and a sensor 74 which is responsive only to the modulated signalof the source. In the preferred embodiment illustrated, the source andsensor are mounted to the same side of the strand being drawn and sofocused that the beam from the source impinges upon the strand andbounces back therefrom to the sensor. Thus, so long as the strand isintact, the sensor senses its presence.

The source, sensor, and power supply of the detector may take anysuitable commercially available form. It is preferred, however, thatthis source be of the modulated signal type which generates a highenergy beam near the infrared spectrum. One suitable supplier for thisequipment has been found to be Opcon, Inc. of Everett, Wash. Thiscompany's 1160/1260 Series Detector and 8161B-1X1 PowerSupply/Demodulator have proved suitable. The use of a modulated signalin the detector has the advantage that the sensor responds only to themodulated energy beam of the source. This means that extraneous lighthas no adverse effect on the detector. The bounce-back mountingarrangement employed in the preferred embodiment has the advantage thatthe detector elements are all to one side of the strand being monitored.

The structure of the bulk gas supply nozzle 28 can best be seen fromFIGS. 1, 2 and 4-10. The nozzle comprises: a body 76 having a chamber 78formed therein; an inlet conduit fitting 80 establishing communicationbetween the interior of chamber 78 and a supply conduit 82 for supplyinggas to the nozzle; a plurality of discharge conduits 84 extendingthrough the top of the body 76 into communication with the chamber 78;and, a valve 86 interposed in each of the conduits 84 to selectivelycontrol flow therethrough. Each valve 86 comprises; a cylindrical bore88 formed in the body 76 in intersecting relationship with the conduit84 associated with the valve; a cylindrical valve core 90 receivedwithin the bore for longitudinal and rotational movement relative to thebore, said core having a passage 92 extending transversly therethroughfor select alignment and misalignment with the associated conduit 84; aknob 94 fixed to the end of the core 90 externally of the body 76; acompression coil spring 96 interposed between a shoulder 98 formed onthe core 90 and an end wall 100 at one end of the bore 88, said springfunctioning to normally bias the core toward a position wherein thepassage 92 is aligned with the conduit 84 (i.e., to the left as viewedin FIGS. 4, 5 and 8); an adjustable stop screw 102 threadably receivedin the knob 94 and disposed for an abutting engagement with the body 76to limit movement of the core 90 in response to the biasing action ofthe spring 96; a groove 104 formed across one end of the core 90; and, aplate 106 received within the body 76 for slideable receipt in thegroove 104 when the axes of the conduit 84 and the passage 92 are inaligned or parallel relationship.

Flow through a valve 86 and its associated conduit 84 can be selectivelyvaried by adjustment of the screw 102 to alter the degree to which thepassage 92 of the valve core is aligned with the conduit. A valve 86 maybe employed to completely close the conduit 84 associated therewith bypulling the knob 94 to disengage the groove 104 from the plate 106 andthen turning the knob so as to engage the end of the core with the plate106. In order to restore a closed valve 86 to the adjusted flowcondition, it is simply necessary to turn the knob 94 to align thegroove 104 with the plate 106 and then to release the knob. Release ofthe knob permits the spring 96 to bring the set screw 102 back intoengagement with the body 76.

As viewed from top to bottom, the three valves in FIG. 4 are in thefully opened, partially restricted, and fully closed positions. FIGS. 5,6 and 7 illustrate the partially restricted condition in detail. FIGS.8, 9 and 10 illustrate the fully closed condition in detail.

The overall power supply and control circuitry is diagrammaticallyillustrated in FIG. 3. The principal elements of the control circuitcomprise a temperature control unit 108; an operator control panel 110;and a main control box 112. Power is supplied to the main control box bypower leads 114. This power drives the entire system and, through thecontrol circuitry, is selectively employed to energize and control thevarious elements of the system.

The operational elements of the system comprise; a transformer 116coupled to the temperature control 108 and having input leads 118connected to the temperature control 108 and output leads 120 connectedto terminals 122 at opposite sides of the orifice plate 20; a blower 124supplied with power from the main control box 112 by leads 126 andhaving an output pipe 128 connected to the supply conduit 82 of the bulkgas supply nozzle 28; a pressure regulator 130 interposed in the pipe128 upstream of a manual control valve 132; a spill pipe 136 interposedin the pipe 128 downstream of the valve 132; a solenoid operated shutoffvalve 138 interposed in the spill pipe 136 and having power supply leads140 connected to the main control box 112; a manually operated flowcontrol valve 142 incorporated into the spill pipe 136 downstream of thevalve 138 to selectively restrict the flow through the pipe; a highpressure air supply conduit 144 having one branch 146 leading to thepneumatic cylinder 42 and another branch 148 leading to a pair ofconduits 150 connected to the opposed gas supply nozzles 30; pressureregulator 152 within the conduit 144 upstream of the branches 144 and146; a solenoid operated shutoff and spill valve 154 interposed in thebranch 146 and having input leads 156 connected to the main control box112; a solenoid operated shutoff valve 158 interposed in the branch 148and having input leads 160 connected to the main control box 112;manually operated flow restrictor valves 162 interposed in the conduit150 to provide for the selective adjustment of air supplied to the gassupply nozzles 30; a precision control 164 for the winder 26; and, astart-stop switch 168 connected to the control box 112 by leads 166 andto the precision control 164 by leads 170.

Leads 172 connect the temperature control unit 108 to a thermocouple 174within the bushing assembly 10. Through the thermocouple connection andthe coupling of the temperature control and the transformer 116, thecontrol functions to control resistance heating of the orifice plate 20to maintain constant the temperature of the glass within the bushing.The control 108 is connected to the main control box 112 by leads 176.These leads together with the circuitry within the main control boxprovide for the insertion of resistances into the temperature circuitryto selectively vary the temperature of the bushing in response to thecommand of the operator panel 110.

The operator control panel 110 is connected to the main control box 112by leads 178. Through these leads, and the manual control switches onthe panel, logic circuitry within the control box is selectivelyactivated. In FIG. 3, the legends on the operator control panel 110identify the function of the various switches and monitoring lights onthe panel. The legends on the control box 112 identify, in generalterms, the circuitry within the box. As shown, the circuitry is depictedas being an electrical relay system. It is also contemplated that anelectronic system could be employed in place of the delay system.

The temperature switch on the control panel 110, through the circuitrywithin the control box 112, provides for the selective adjustment oftemperature to any one of three temperatures, namely, normal, cool andcold. Normal is typically in the range of 2100° to 2300° F. Cool isapproximately 40° F. less than normal and cold is approximately 80° F.less than normal. Control is effected by switching parallel resistancesinto the thermocouple suppression bridge within the control 108 throughmeans of relays within the control box. In the preferred embodiment, thecircuitry within the control box requires that the temperature controlswitch be in the normal position in order for the winder to operate.

The bulk air switch has two positions, namely, "on" and "off." In the onposition, the relays within the control box 112 function to energize theblower 124 to supply air to the bulk supply nozzle 28, and to energizethe valve 154 to extend the carriage 34. In the off position, the relayswithin the box 112 de-energize the blower 124 and the valve 154 toterminate the supply of air to the nozzle 28 and to retract the carriage34. In a multiple bushing facility where the blower 124 is employed tosupply bulk gas to a number of bushings, the blower runs continuouslyand solenoid valves are employed to selectively turn on or off thesupply of bulk gas to the respective nozzles.

The clear air switch has two positions, one where the solenoid 158 isenergized to open the conduit 148 and the other where the solenoid ispermitted to close the conduit. The solenoid 158 is energized throughthe relays within the box 112.

The spray switch has an "on" position wherein it allows the valve 68 tobe automatically controlled by relays within the box 112 and an "off"position wherein it closes the valve. Control of the valve is effectedthrough means of the relays within the box 112 and leads 180 extendingfrom the box to the valve.

The reset switch has two positions. In one, the breakout detector islocked out of the circuit with two of the time delays locked out. Theoperation of the system with the reset thus positioned is depicted bythe logic flow diagram of FIG. 11. In the other position, the resetenergizes the full break-out mode of operation, including all timedelays and the break-out detector. The operation of the system with thereset in the latter position is depicted by the logic flow diagram ofFIG. 12. The functions of the reset switch are achieved through means ofthe relays within the box 112.

The initial boxes in the logic flow diagrams of FIGS. 11 and 12 indicatethe positions of the respective switches on the control panel 110 at thecommencement of operations. The only difference in these boxes is thatin FIG. 11 the reset is in the reset position, while in FIG. 12 thereset is in the auto position.

With the switches on the operator panel positioned as shown in the leadbox in FIG. 11, operation of the bushing assembly is initiated bystarting the winder. This, in turn, activates the first time delaywithin the box 112 and, after running of the delay, the relays withinthe box function to open the spill air valve 138 and close the sprayvalves 68. At this point, assuming the temperature switch is in thenormal condition, the collet proceeds to draw a full package, at thetermination of which the winder control energizes a call lamp for thebushing operator. If for any reason the temperature switch is turned tothe cool position or the cold position, the collet will stop after thespill air open/spray nozzle off step shown in FIG. 11.

With the reset in the auto position at the commencement of bushingoperation, as depicted in FIG. 12, the operation will be the same asthat described above with respect to FIG. 11, assuming that no break-outis sensed during operation and that the operator arrives promptly afterthe call lamp is energized by the operation of the winder controls andthe relays within the box 112. If a break-out is detected duringoperation, or if the operator fails to arrive after a time delayfollowing the call lamp on signal, the system will go to the second lineof the logic flow diagram of FIG. 12. As can be seen from this line, thefirst step that then occurs is that an alarm is activated and this, inturn, is followed by a time delay to give the operator a chance toarrive and stop the bushing operation. If the operator does not arrive,then the system goes to the break-out mode and the following stepsautomatically take place: the temperature of the bushing is lowered tothe cool level (minus 40° F. from normal); the slide carriage 34 isretracted; the bulk air blower 124 is stopped; the clearing air valve158 is opened; and, the collet is shut off. All of these steps areachieved through means of the logic circuitry and various elementswithin the control box. The effect of this automatic break-out mode isto shut down the drawing operation, while preventing excessive coolingof the orifice plate which might result in the accumulation of a largeball of hardened glass at the plate. Partial clearing of the floodedplate will slowly occur even in the absence of the operator.

CONCLUSION

From the foregoing description it is believed apparent that the presentinvention enables the attainment of the objects initially set forthherein. It should be understood, however, that the invention is notintended to be limited to the specifics of the illustrated embodiment,but rather as defined by the illustrated embodiment, but rather asdefined by the accompanying claims.

What is claimed is:
 1. An improved nozzle for use in directing bulk gasagainst a bushing used for the drawing of glass fiber, and nozzlecomprising: a body having a chamber therein; inlet means to provide forthe introduction of gas into the chamber; a plurality of conduitscommunicating with the chamber to provide for the discharge of gastherefrom; and slide valves disposed within at least some of saidconduits, said valves being selectively adjustable to vary the flowthrough the respective conduits, said valves each including acylindrical valve core arranged for longitudinal and rotational movementand having a passage extending transversely therethrough for selectalignment and misalignment with the conduit associated therewith, andlock means to selectively lock the core in a position wherein thepassage in the core is misaligned relative to the conduit to completelyclose the conduit, and means to lock the core being selectively operableto lock or release the core and, in the released condition, functioningto longitudinally guide the core.
 2. A nozzle according to claim 1,wherein each valve further comprises resilient means operable uponrelease of said lock means to normally bias the core longitudinallytoward a position wherein the passage within the core is longitudinallyaligned with the conduit within the body associated with the valve.
 3. Anozzle according to claim 2, wherein each valve further comprises: setscrew means to selectively adjust the degree to which the passage of thevalve core is aligned with the conduit when released for movement by theresilient means.
 4. In combination with a glass fiber drawing assemblyhaving an orifice plate with a generally planar undersurface perforatedby a multitude of drawing orifices in closely spaced relationship toeach other, a winder spaced beneath the plate for drawing fibertherefrom, and support means mounted between the orifice plate andwinder outside of the path of glass fiber being drawn from the plate,the improvement comprising: a supply nozzle associated with said supportmeans for directing bulk gas against the undersurface of the plate, andnozzle including a body having a chamber therein; inlet means to providefor the introduction of gas into the chamber; a plurality of conduitscommunicating with the chamber to provide for the discharge of gastherefrom; and slide valves disposed within at least some of saidconduits, said valves being selectively adjustable to vary the flowthrough the respective conduits, said valves each comprising: acylindrical bore formed within the body in intersecting relationshipwith the conduit associated with the valve; a cylindrical valve corereceived within the bore for longitudinal and rotational movementrelative to the bore, said core having a passage extending transverselytherethrough for select alignment and misalignment with the conduit;grip means on said core to enable said core to be moved relative to thebody; resilient means to normally bias the core longitudinally toward aposition wherein the passage within the core is longitudinally alignedwith the conduit within the body associated with the valve; and means toselectively lock the core against movement responsive to the resilientmeans in a position wherein the passage in the core is misalignedrelative to the conduit associated with the valve to completely closethe conduit, said means to lock the core being selectively operable tolock or release the core against movement responsive to the resilientmeans and, in the released condition, functioning to guide the corelongitudinally within the bore.
 5. In a combination according to claim4, the improvement wherein each valve further comprises: set screw meansto selectively adjust the degree to which the passage of the valve coreis aligned with the conduit.